1. Field of the Invention
The present invention relates to a novel an image sensing apparatus for use in a color facsimile device, color copying apparatus, color scanner, or similar devices and to a novel method for sensing color images.
2. Description of the Related Art
In the art, the following three arrangements are known for sensing a color image:                a) A single light source, such as a xenon lamp, and color photoelectric conversion devices, each having its own color filter formed on its surface;        b) A single light source, such as a xenon lamp, and a color photoelectric conversion device in conjunction with a plurality of mechanically switched color filters; and        c) Three light sources such as fluorescent lamps which emit light of R, G, and B (red, green and blue), and which are switched during an image sensing operation.        
These known arrangements have the following problems. When the arrangement (a) used to sense a color image, three different photosensors corresponding to RGB colors are required. Furthermore, it is required to form a color filter on the surface of each sensor element. Thus, this arrangement is expensive. In the case of the arrangement (b), it is required that the light source emit high-intensity light to compensate for absorption of light by the color filters. Furthermore, the mechanism of switching the color filters is expensive, and it is difficult to realize a small-sized image sensing apparatus. In the arrangement (c), for example, three fluorescent lamps which emit light with spectrum peaks at three different wavelengths are used. However, fluorescent lamps exhibit long persistence. Furthermore, a long time is needed to stabilize the light intensity after being turned on. As a result, a complicated circuit is needed to control the operation of turning on the fluorescent lamps